About get the values from SQLite

Question

I wanna set a textview as the values from SQLite when I click the ListView Here is my way:

myListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
public void onItemClick(AdapterView arg0, 
android.view.View arg1, int arg2, long arg3) { 
myCursor.moveToPosition(arg2); 
setContentView(R.layout.main2); 
_id = myCursor.getInt(0); 
textStudyUID.setText(myCursor.getString(0)); 

But there is a exception, here is the log:

07-05 12:37:16.613: ERROR/AndroidRuntime(17689): java.lang.NullPointerException
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at irdc.sqlitetest2.SQLiteTest2$1.onItemClick(SQLiteTest2.java:53)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at android.widget.AdapterView.performItemClick(AdapterView.java:284)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at android.widget.ListView.performItemClick(ListView.java:3285)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1640)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at android.os.Handler.handleCallback(Handler.java:587)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at android.os.Handler.dispatchMessage(Handler.java:92)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at android.os.Looper.loop(Looper.java:123)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at android.app.ActivityThread.main(ActivityThread.java:4363)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at java.lang.reflect.Method.invokeNative(Native Method)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at java.lang.reflect.Method.invoke(Method.java:521)

07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)

07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
07-05 12:37:16.613: ERROR/AndroidRuntime(17689): at dalvik.system.NativeStart.main(Native Method)

Here is the full code:

public class SQLiteTest2 extends Activity {

private DoDB ToDoDB;<br>
private Cursor myCursor;<br>
private int _id;<br>
private ListView myListView;<br>
public TextView textStudyUID;<br>
protected ListAdapter adapter1;<br>

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

myListView = (ListView)findViewById(R.id.ListView);
textStudyUID = (TextView)findViewById(R.id.widget40);
ToDoDB = new DoDB(this);
myCursor = ToDoDB.select();
SimpleCursorAdapter adapter1 = new SimpleCursorAdapter(this,R.layout.list,myCursor,new String[]{DoDB._StudyUID},new int[]{R.id.listTextView1});
myListView.setAdapter(adapter1);


myListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView arg0, android.view.View arg1, int arg2, long arg3) {
myCursor.moveToPosition(arg2);
setContentView(R.layout.main2);
_id = myCursor.getInt(9);
textStudyUID.setText(myCursor.getString(0));
}
});

Answer 1

You'll not be able to access myCursor inside the anonymous function (onItemClick) due to scoping, but the cursor you're after is already being passed to the function. Retrieve it using:

CursorAdapter adapter = (CursorAdapter) arg0.getAdapter();
Cursor myCursor = adapter.getCursor();

You may want to consider naming the parameters correctly to improve readability. I.e.:

public void onItemClick(AdapterView<? extends Adapter> parent, View v, int position, long id)